But the cheapest way to get foreign cash is to use an ATM card issued by a bank that does not assess network fees, and to withdraw the money from an ATM that does not have an ATM fee. (Most ATMs outside the USA do not have a fee.)
Which banks could you recommend that do not charge fees for withdrawing $ from foreign country, foreign institution ATMs?
BTW, the US practice of charging holders of foreign institution ATM cards is spreading to some other countries. Canadian institutions charge, and I believe Korean banks do as well.